Evaporator control



w, L. DE mm. EVAPORATOR CQNTRQL. APPLICATION FILED SEPT. 6, 1916-Patented Aug. 1 6,192i.

2 SHEETS-SHEET W/TNESSESN -i V QR; f M W r f A TTORNEY' INVENTOR ATTO Yw. L. DE BAU FRE. EVAPORATOR CONTROL.

' APPLICATION FILED SEPT- 6119's. 1,3 7,475, Patented Aug. 16, 1921.

. '2 SHEETS- SHEET 2.

on w .QPW M m I 5 u N hm J m\ w WILLIAM L. DE BAUFRE, 0F ANNAIOLIS,MARYLAND.

EVAPORATOR CONTROL.

.Speciflcation of Letters Patent. Patented Aug. 16, 1921.

Application filed September 6, 1916. Serial No. 118,726.

To all whom it may concern.

Be it known that I, WILLIAM L. DE BAU- FRE, a citizen of the UnitedStates, residing at Annapolis, in the county of Anne Arundel, in theState of Maryland, have invented a certain new and useful EvaporatorControl, of which the following is a specification. My invention relatesto improvements in evaporator controls-and has for its object theelimination of constant attention during operation of evaporators, byproviding means of automatically controlling the supply of the primaryvapor, the rate of feed of the solution to be evaporated and the rate ofdischarge of the concentrated solution.

A furtherv object of my invention is the utilization of the heat in theconcentrated solution discharged from evaporators.

A further object of my invention is the improving of the economy anddurability of evaporators.

And a further object of my invention is the providing of means to insurethe safety of evaporators.

With the foregoing and other objects in view, my invention consists ofthe novel construction, combination and arrangement of parts ashereinafterspecifically described and illustrated in the accompanyingdrawings, wherein is shown the preferred embodiment of my invention, butit is understood that changes, variations and modifications can beresorted to which come within the scope of the claims hereunto appended.

In the drawings of the herein described embodiment of my inventionFigure 1 is a diagrammatic view of an evaporator system, showing anevaporator in its relation to the source of primary vapor, to the sourceof solution feed, to the utilization of the various discharges bypreheaters, feed heaters, etc, and to automatlc means of controlling therelations involved; and Fig. 2 is a similar view with modified forms ofapparatus. Similar numerals refer to similar parts throughout theseveral views.

The source of primary vapor 1 may be an ordinary coal or oil firedboiler as shownin Fig. 1, or an electrically heated boiler as indicatedin F ig.- 2. From boiler 1, the primary vapor is supplied through vapormain'2 to evaporator 3. When evaporator feed pump 4 and-boiler feedpump, 5 are vapor operated as represented in Fig. 1, the operating vaporvmay also be supplied from installation on shipboard).

-may be discharged through exhaust main 8 and, if desired, through pipe9 into the evaporator as shown in Fig. 1. Evaporator feed suction pipe10 from some source (such as the sea when installed on shipboard), anddelivers it through pipe 11 and evaporator preheater 12 and pipe 13 tothe solution space of evaporator 3.

The discharge of concentrated solution from evaporator 3 is controlledby weir box 14 and trap 15. The concentrated solution is drawn through apipe from the placeof its greatest density (generally near the bottom ofthe solution s ace), and is discharged through the coil in t e boilerfeed heater 16 on its way to waste (to the sea in case of In Fig. 2 aclosed feed heater is depicted, while in Fig.1 the feed heater 16consists merely of a coil immersed in the feed tank 17. The weir box 14whether it be located outside of the evaporator shell or within the samemust be connected to the upper part of the solution space of evaporator3 by a pressure equalizing pipe 18, in order to maintain the samepressure within weir box 14 as within the evaporator shell 3. In Fig. 1theweir box 14 is shown within the evaporator shell; in Fig. 2 it isshown located outside of the evaporator shell and within the shell ofthe boiler feed heater 16. Vapor from evaporator 3 passes through pipe19 to the coil in preheater 12 where it is condensed, the condensedvapor being drained from this coil by trap 20 and discharged into tank21 provided for it.

pump 4 gets its supply-of solution through The vapor condensed in thecoil within evaporator 3 is drained by trap 22 and dis charged into feedtank 17,.or storage tank 23 ,as desired.

The liquid to be vaporized in boiler 1 is drawn by boiler feed pum 5from feed tank 17 and is delivered by t is pump into the boiler eitherdirectly as indicated in Fig. l, or through the coil in closed feedheater 16 as represented in Fig. 2. In order to regulate the rate ofsolution feed to evaporator l 3, an automatic control valve 24. isprovided, having a connection 25 to the evaporator.

In Fig. 1 this control valve is in the vapor line to the evaporator feedpump 4, and it controls the rate of feed by governing the speed of thepump; in Fig. 2 this control valve is in the delivery pipe 11 andthrottles the feed directly. Control valve 24 is shown on a by-passconnection to facilitate the repair of the valve Without interruptingthe operation of the evaporator.

As the vapor above the liquid in evaporator 3 is in the saturated state,there is for each pressure a definite value of its temperature and ofits density to correspond. Consequently, the temperature or the densityof the vapor may serve to operate control valve 24 according to thevapor pressure. Also, connections 25 may be made below the liquid levelsince the properties of the liquid vary with those of the vapor above.

In this description and in the drawings Fig. 1 and Fig. 2, the feed ofsolution is controlled by the pressure within the evaporator 3 and'thedischarge of solution is controlled by the solution level therein.However, the same results may be accomplished with the controlsreversed, that is, the feed controlled by the height of the liquid andthe discharge controlled by the pressure.

An orifice of fixed and predetermined dimensions is provided in the pipebetween vapor main 2 and the coil in evaporator 3 to supply the properquantity of vapor for the working capacity of the evaporator. In Fig. 1this orifice 27 is a part of the nozzles in ejector 26, in Fig. 2 it isin a diaphragm in the pipe. A safety valve 28 having a capacitycorresponding to that of the fixed and predetermined orifice, is mountedon the solution chamber of evaporator 3. Evaporator stop valve 29 ismounted in the pipe between primary vapor main 2 and the fixed orifice27 A water level gage 30 and a pressure gage 31 are provided onevaporator 3 to aid in its operation as described later.

The operation of my invention is as fol- I lows Assume the apparatus tobe arranged substantially as represented either in Fig. 1 or Fig. 2,with the proper vapor pressure attained in boiler 1 and vapor main 2,but the evaporator 3 not yet in operation. Start evaporator feed pump 4and fill the evaporator to its working level as seen in level gage 30.The by-pass of control valve 24 must be temporarily opened since thecontrol valve will not open until its set working pressure has beenattained in the evaporator to which the means of control are connected.Referring to Fig. 1, the valves on exhaust main 8 should be open and thevalve on pipe 9 should be closed while starting the vapor driven pump 4.They may be reversed later if desired. The whole evaporation system isnow automatically put into operation by opening wide the evaporator stopvalve 29,

which of course should be opened slowly to prevent hammer in the pipes.All functions are cared for automatically during operation, provided thevapor pressure available at evaporator stop valve 29 is within theworking limits required. Thus, the solution feed control valve 24automatically regulates the rate of solution feed to the evaporatoraccording to the pressure therein as indicated on pressure gage 31 andthe weir box 14 and trap 15 automatically regulate the rate of dischargeof concentrated solution by maintaining a nearly constant solution levelas may be seen in level gage 30.

In the system of evaporation here described, a constant flow of thesolution is maintained through the evaporator, this flow being necessaryto carry off the latent heat of the primary vapor condensed therein.With a certain quantity of primary vapor available, as determined by thevapor pressure at valve 29 and the fixed size of orifice 27, the rate ofsolution flow will be a function of the temperature of the source of thesolution and the temperature within the evaporator (or the pressurewithin the evaporator, since the pressure. must correspond to thetemperature). A higher rate of flow than this relation gives wouldreduce. the pressure in the evaporator, and a lower rate would increasethe pressure. Hence the proper rate of flow will be obtained byregulating it according to the pressure. he coils within evaporator 3and preheater 12 are automatically drained by traps. The heating of theliquid fed to boiler 1 automatically takes place in feed heater 16, thusreturning to the system heat which would otherwise be discharged towaste. The latent heat of the primary vapor being carried off by theconcentrated solution discharged from the evaporator, the solutionwithin the evaporator attains a maximum concentration much lower thanthat attained under the usual method of operation. Consequently lessdifficulty will be experienced with scale and the durability otthematerials employed in the construction of the evaporator Will beincreased.

Should vapor pipe 19 become closed or the pressure control valve 24 failto operate properly while stop valve 29 is open, there may be anaccumulationof pressure in evaporator 3. Safety valve 28 will then automatically open to prevent an excessive rise of pressure. The vaporgenerated within the evaporator will never be but very slightly greaterthan the quantity of primary vapor supplied through the orifice 27.Hence,

safety valve 28 will always control thepressure in the solution spacewithin safe limits, if made with a normal capacity equal to that of theorifice at the maximum available primary vapor pressure. The shell ofthe evaporator may thus be safely designed for 9.

, trolled by the vapor in the solution space of pressure lower than thatof the primary vapor. The primary vapor space, however, should bedesigned to safely withstand the maximum available boiler pressureunless a second safety valve of proper capacity is mounted thereon.

Having thus described my invention what I claim and desire to secure byLetters Patent is. v

1. In an evaporator control, an evaporator and a preheater in closedhydraulic connection embracing a feed into the preheater of a solutionwhich is fedinto the evaporator, means in the preheater for condensingvapor from said evaporator, and an automatic control of solution feed tosaid evaporator consaid evaporator. 2. In an evaporator control, anevaporator containing evaporating and condensing compartments, means ofsupplying the said evaporating compartment 'w1th solution to beevaporated, a safety valve onthe said evaporating compartment, means forsupplying a heating vapor of a definite maximum pressure to saidcondensing compartment and means for limiting the rate of supply ofvapor to said condensing compartment to less than the capacity of saidsafety valve by an orifice of fixed and predetermined capacity throughwhich the said vapor flows.

'3. In an evaporator control, an evaporator and automatic means forcontrolling the flow of solution through the said evaporator operated bythe solution level therein in I combination with the pressure,temperature ordensity of the vapor therein. 4. In an evaporator control,an evaporator and automatic means for controlling the flow of solutionthrough the said evaporator comprising means of maintaining a constantsolution level therein in combination with j means for maintaining aconstant pressure therein.

' 5. In an evaporator control, an evaporator,

an automatic control of solution feed to said evaporator controlled bythe vapor in the solution space of. saidevaporator, automatic means formaintaining .a constant solution level in said evaporator, and automaticmeans for withdrawing the solution from a place of its greatest density.

6. In an-evaporator containing a condensing compartment and anevaporating compartment control, an evaporator, an. automatic control ofsolution feed to said evaporator the latent'heat of the oratorcontrolled by the vapor in the said evaporating compartment, andautomatic means for maintaining a constant solution level in saidevaporator embracing a chamber with passages. extending both above andbelow. the solution level in said evaporating compartment.

7. In an evaporator control, a system comprising an evaporator and apreheater for heating the solution fed to said evaporator, means forcondensing the vapor from said evaporator within said system, andautomatic means for removing from the system in the solution dischargedfrom sald eva said evaporator.

8.- In an evaporator control, a system comprising an evaporator and apreheater for heating the solution fed to said evaporator,

means for condensing the vapor from said evaporator within said system,and automatic means for removing from the system in the solutiondischarged from said evaporator the latent heat of the steam suppliedsaid evaporator operated by the vapor and the solution'level in saidevaporator.-

9. In an evaporator control, asystem comprising an evaporator and apreheater forheating the solution fed to said evaporator, means forcondensing. the vaporfromsaid evaporator. within said system,'-automatic means for controllingthe rate of solution fed tosaidfevaporator by the va'tporin said evaporator, and automatic meansfor con the solution discharged from said evaporator, and automaticmeans for controlling the flow of solution through said preheater,evaporator and feed heater by the vapor and the solution level insaidevaporator.

WI LIA L. DE BAUFRE.

Witnesses:

THOMAS W. KINKAID, J, S. KAUFFMAN.

steam supplied

